Related Experiment Video
Updated: Jul 8, 2026
Single Molecule Methods for Monitoring Changes in Bilayer Elastic Properties
Published on: November 3, 2008
What accounts for the difference between singlet phenylphosphinidene and singlet phenylnitrene in reactivity toward
John Morrison Galbraith1, Peter P Gaspar, Weston Thatcher Borden
1Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA.
Abstract:
(8/8)CASSCF and (8/8)CASPT2 calculations have been performed in order to investigate the potential surface for the ring expansion of the (1)A(2) state of phenylphosphinidene (1c) to 1-phospha-1,2,4,6-cycloheptatetraene (3c). Unlike the comparable ring expansion of the (1)A(2) state of phenylnitrene (1b) to 1-aza-1,2,4,6-cycloheptatetraene (3b), ring expansion of 1c to 3c is computed to be quite endothermic. Nevertheless, cyclization of 1c, to form the bicyclic intermediate 2c in the ring expansion reaction, is computed to be only slightly more endothermic than the comparable cyclization reaction of 1b to 2b. The origins of these differences between the ring expansion reactions of 1b and 1c have been elucidated through the calculation of the energies of relevant isodesmic reactions.
Related Concept Videos
04:01VSEPR Theory and the Effect of Lone Pairs
03:05Acid Strength and Molecular Structure
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
02:16Brønsted-Lowry Acids and Bases
02:34Molecular Structure and Acidity
The size effect explains the change in atomic size on acidity. When comparing the acids formed from elements that belong to the same column in the periodic table, their atomic sizes...
01:28Structures of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
01:31Substituent Effects on Acidity of Carboxylic Acids